US2443653A - Control system - Google Patents

Description

June 22, 1948. w. H. CUTTINO ETAL CONTROL SYSTEM 3 Sheets-Sheet 1 Filed Dec. 31, 1943 INVENTORS MY/iam HCu/fmo andMer/Eflarn.

./ TTORNE June 22, 1948. w. H. CUTTINO EI'AL 2,443,653

CONTROL SYSTEM Filed Dec. 31, 1943 5 Sheets-Sheet 2 WITNESSES: g we INVENTORS M/bam f1- Cuff/no X 0/; er 0 f7 gym *1/ W LLMJJ June 1948. w. H. CUTTINO ETAL 2,443,653

CONTROL SYSTEM Filed Dec. 31, 1943 3 Sheets-Sheet 3 wnmzssss; INVENTORS Patented June 22, 1948 UNITED STATES PATENT OFFICE CONTROL SYSTEM Application December 31, 1943, Serial No. 516,374

12 Claims. (Cl. 175-375) Our invention relates, generally, to control systems, and it has reference, in particular, to circuit breaker control systems.

Generally stated, it is an object of our invention to provide a control system for circuit breakers which is simple and inexpensive to manufacture and is positive in its operation.

More specifically, it is an object of our invention to provide for automatically operating a circuit breaker in response to predetermined conditions of a load circuit, and to provide for looking the circuit breaker open when it opens in response to another predetermined condition of the load circuit.

An important object of our invention is to provide for operating a control switch associated with a circuit breaker only when the circuit breaker opens in response to the occurrence of a predetermined fault-condition.

Another object of our invention is to provide for mechanically operating a circuit breaker control switch in response to predetermined movement of the circuit breaker operating mechanism, so as to prevent reclosure of the circuit breaker after it has opened in response to an over-current condition.

Yet, another object of our invention is to provide for mounting a circuit breaker control switch in conjunction with the operating mechanism of the circuit breaker, so that the switch operates in response to predetermined movement of the operating mechanism.

Still another object of our invention is to provide a simple and effective control circuit for effecting connection to and disconnection from a load circuit of a bank of capacitors in response to voltage, current or reactive kva. conditions, while providing for locking the circuit breaker open in the event that it is tripped due to overcurrent conditions.

It is also an important object of our invention to provide for mechanically operating a circuit breaker control switch in response to movement of the circuit breaker operating mechanism, when the circuit breaker is tripped due to over-current conditions, so as to prevent reclosure of the circuit breaker.

Other objects will, in part, be obvious and will, in part, be explained hereinafter.

In accordance with the principles of our invention, the automatic reclosure of a circuit breaker utilized for controlling the connections of a bank of capacitors or the like, to a power system is prevented when the circuit breaker trips in response to an over-current condition, by using a 2 control switch having normally closed contact members in the recioslng circuit of the circuit breaker which are mechanically operated in response to predetermined movement of a portion of the circuit breaker operating mechanism only when it trips due to an over-current condition.

For a more complete understanding of the nature and scope of our invention, reference may be made to the accompanying drawings, in which,

Figure 1 is a partially sectioned side elevational view broken out, in part, of one pole of a circuit breaker embodying the principle features of the invention,

Fig. 2 is an enlarged fragmentary side eleva tional view of the control switch operating mechanism actuated to the non-operating position,

Fig. 3 is spatially sectioned side elevational view broken out, in part, of one pole of another type of circuit breaker embodying the invention in another of its forms,

Fig. 4 is a bottom plan view of the control switch operating mechanism shown in Fig. 3,

Fig. 5 is a diagrammatic view of a control system embodying the invention in connection with a circuit breaker of the type shown in Fig. 1, and

Fig. 6 is a diagrammatic view of a control system embodying the invention in connection with a circuit breaker of the type shown in Fig. 3.

Referring to Fig. 1, the reference numeral ill may denote, generally, a circuit breaker of the type such as is shown and described in detail in Patent No. 2,214,471 which issued on September 10, 1940, to L. R. Ludwig et a1., and with which control means designated generally by the numeral l i may be incorporated in accordance with the principles of our invention.

The circuit breaker Ill may comprise a panel I2 of insulating material, having terminals l3 and it connected to stationary contact members 15 and 18, respectively. A main moving contact member i1 may be mounted on a switch arm it, which is pivotally mounted on a frame IQ for engaging the stationary contact members. Auxiliary arcing contact members 20 and 2! may be provided on the stationary contact member is and the switch arm il in a well-known manner.

A spring 13 may be provided for biasing the switch arm it to the open position, and an operating mechanism 24 may be provided for operating the switch arm to and retaining it in the closed position. The operating mechanism 24 may, for example, comprise an actuating lever 25 and an operating member, which may be pivotally mounted on a pin 27 in the frame is. an op rating rod 28 may be connected to the operating member 26 to provide for connection to closing means such as a solenoid (not shown). The actuating member may be connected to the switch arm l8 by means of a link 29, and means such as the latch members and 3| may be provided for normally and releasably engaging a roller 32, mounted on the operating member 26, for retaining the actuating lever 25 and the operating member 26 in operating relation. A latch member 33, which may be pivotally mounted on a pin 34 in the frame It), may be provided for normally retaining the roller 32 in operating relation and releasing the roller 32 when actuated, so as to effect opening of the circuit breaker. A trip bar 35 pivotally mounted on the pin 34 by means of arms 36 may be connected to the latch member 33 as well as the latch members of other poles of the circuit breaker for operating themv simultaneously. Operation of the trip bar 35 and the latch member 33 may be efiected in a plurality of ways, such as by means of a shunt trip device 31, a current responsive overload device 38, or manual trip means 39.

The shunt trip device '31 may comprise a solenoid 46 for actuating an armature 4!. The armature operates a'trip bracket 42 which maybe operatively associated with the trip bar 35 by means of a set screw 43 engaging the arm 36. The bracket 42 may be secured to a lever 44, pivotally mounted on the pin 34 or an extension thereof. The lever 44 may be provided with an extension 45 for reasons which will be explained hereinafter.

When the solenoid 40 is energized, the armature 4i is drawn downward, rotating the trip bracket 42 in a clockwise direction, so that the 'set screw 43 engages the arm 38, and moving it clockwise. The latch member 33 is thereby moved in a clockwise direction, so as to release the roller 32 and effect opening of the circuit breaker l6.

The overload device 38 may comprise a trip arm 41, which may be operably connected to the latch member 33 by means of the trip bar 35 for actuating it to release the roller 32 and open the circuit breaker. Operation of the trip arm 41 may be effected by means of an-armature 48, actuated by means of an operating winding 49, which may be connected in series circuit relation between the lower terminal l3 and the stationary contact member l5.

The manual trip means 39 may comprise a push rod 5| adapted to actuate a trip arm 52 secured to the trip bar 35 in the clockwise direction, thereby operating the latch member 33 to release the roller 32.

In order to provide for locking the circuit breaker in the open position when it is tripped in response to an overload or over-current condition, control means denoted, generally, by the numeral H is provided. The control means may, for example, comprise a control switch 53 which may be mounted on the frame I! by means of a bracket 54 and provided with an actuating member 55 for opening normally closed contact members adapted to be connected to provide an operating circuit for the operating solenoid (not shown) of the circuit breaker. Operation of the control switch 53 may be effected by a transverse pin 56 which may extend between the opposite sides of a substantially U-shaped operating member 51. The operating member may be normally positioned so as to maintain the pin 56 in operating relation with the actuating member 55 of the control switch 53, by means of a support member 58 which may be pivotally mounted on the control switch bracket 54 by means of a pin 59. A spring 60 may be provided for retaining the operating member 51 and the support member 58 in the proper operating relation. Operation of the operating member 51 may be effected by a connecting rod 62 which may connect the operating member 51 to the actuating lever 25 of the circuit breaker. When the circuit breaker opens in response to an over-current condition, for example, the rod 62 moves downwardly, forcing the transverse pin 56 against the actuating member 55 of the control switch 53 and opening the normally closed contact members thereof.

In order to provide for selectively operating the control switch 53 only in response to over-current fault conditions, suitable means may be provided for rendering the operating means ineffective whenever the circuit breaker is tripped for other than over-current conditions. An arm 64 may be provided being, for example, pivotally mounted on the pin 34 or on a bushing 63 on an extension thereof. The arm 64 may be provided with a stop 65 for engagement by the extension 45 of the lever 44 when it is actuated in the clockwise direction. The arm may also be provided with a substantially U-shaped member 66 at the lower end having spaced apart side portions 61 and 68 positioned on either side of the lower end of the trip arm 52. A stop member 10 may be provided in the side 61 adjacent the suppo t member 53 for normally retaining the operating member 5| in operating relation with the actuating member 55 of the control switch, and moving it out of operating relation therewith whenever the circuit breaker is tripped either by means of the shunt trip device 31 or the manual trip means 39.

As shown in Figs. 1 and 2, whenever the push bar 5| is moved to the left it engages the upstanding side portion 68 of the U-shaped member 66 and the arm 64 is moved in a clockwise direction about the pin 34 at the same time as is the trip arm 52. The stop member 16, which engages the pivotal support member 58, rotates the support member in a counter-clockwise direction about the pin 59. This movement rotates the operating member 51 in a clockwise direction about its point of connection wth the rod 62, so that the transverse pin 56 moves clear of the actuating member 55 of the control switch. Accordingly, when the connecting rod 62 moves downwardly in response to opening of the circuit breaker, the control switch 53 is not operated. and the contact members thereof remain in a closed position, providing an operating circuit for effecting'reclosing of the circuit breaker. Operation of the shunt trip means 31 effects a similar result, since the arm 64 is moved in a clockwise direction by means of the engagement of the extension 45 of the lever 44 with the stop 65 in response to actuation of the armature 4!.

Referring to Fig. 3, the reference numeral 18 may denote, generally, a circuit breaker of the type such as is shown and described in detail in Patent No. 2,322,321 which issued on June 22, 1943, to T. Lindstrom et al., and with which are incorporated control means 86, embodying'the principal features of the invention.

The circuit breaker 18 may, for example; comprise terminals 8| and Ma connected to stationary contact blocks 82 and 83 mounted on a panel 84, and which are adapted to be bridged by means of a moving contact member 85, which maybe mounted on a pivotal switch arm 86. Operation of the switch arm maybe effected by means of a toggle mechanism including toggle members 31 and pivotally connected between a lever member 09 and the switch arm 00. The switch arm 00 may be maintained in the closed position against the tension of an opening spring 90 by means of cooperatin toggle mechanisms 9| and 92 which releasably retain the lever member 09 in the operating position.

Closure of the circuit breaker may be eilfected by means of an operating handle 94 which may be rotated clockwise for actuating a closing lever 95 to directly actuate the switch arm 86 in a counterclockwise direction to the closed position. Operating means comprising a motor 96 and a cam operating mechanism 91 may be provided for electrically operating the closing lever to close the circuit breaker.

Opening of the circuit breaker may be effected by means of an overload device 98, by means of a shunt trip device 99, or by rotating the handle 94 counterclockwise to break the toggle mechanism 9|. The overload device 98 may comprise a laminated magnetic core I00, through which a current carrying conductor IOI passes, and an armature I02. The armature may be disposed to actuate a trip arm I03 connected to a trip bar I04 for operatin a trip pin I05a to break the toggle lever mechanism 92, thereby releasing the lever 09 and permitting clockwise rotation of the lever 09 about its lower right-hand end for effecting opening of the circuit breaker. The shunt trip device 99 may comprise a solenoidl05, for effecting movement of the trip pin I05a to break the toggle mechanism 9I and open the circuit breaker.

In order to provide for preventing reclosure of the circuit breaker when it is tripped in response to operation of the overload or over-current device 90, the control means 90 may be provided. Referring to Figs. 3 and 4, it may be seen that the control means 80 may comprise a suitable control switch I06, which may be provided with normally closed contact members for maintaining an operating circuit for the reclosing motor 96, and which may be biased by means of a spring (not shown) to the open position. An operating member I 08 may be provided for normally retaining the switch I06 in the closed position. This operating member may, for example, comprise a pair of spaced apart levers pivotally mounted on a control switch bracket IIO by means of an arm I I I adjacent one end. An elongated slot I I2 may be provided adjacent the other end for receiving a pin I I3 whereby a lost motion connection may be provided with the switch arm 00 through the medium of a plurality of levers II4a, H41) and H40. This connection insures reclosure of the switch I06 when the circuit breaker is reclosed.

In order to provide for selective operation of the control switch I06, a latch member I I0 may be provided for engaging a projecting pin III on the operating member I08 for retaining the control switch I06 in the closed position. The latch member IIIi may also be provided with a dependent arm II8 adapted to be actuated by the trip lever I03, which is fastened to the trip bar I04 and is actuated by the overload or over current responsive device 98.

Accordingly, when the circuit breaker I0 is tripped, either manually or by means of the shunt trip device 99, the circuit breaker opens and the control switch I06 is retained in the closed position by means of the latch member IIG, so that an operating circuit for the reclosing motor 96 is provided.

Whenever the circuit breaker is tripped by operation oi the over-current device 90, the latch member H6 is actuated in a clockwise direction by means of the trip arm I03. This releases the pin III of the operating member Ill, so that the operating spring of the switch 0 opens the normally closed contact members or the control switch I00, and the operating circuit for the closing motor 00 is interrupted.

Resetting of the control means 00 may be effected either by operating the handle 94 to close the breaker manually, whereupon the lever I I4a actuates the operating member I00 to the latch position, or by pushing a reset button I20 which may be provided with a support member I2I slidably supported on the control switch'bracket IIO by means of suitable hangers I29 and I24. The latch member II6 may be pivotally mounted on the support member I2I by means of a pin I 25, so that it is moved bodily to the left until the latch reengages the pin III of the operating member. Upon release of the support member I2I, the operating spring I26 thereof actuates the operating member to the right, reclosing the contact members of the control switch.

Referring to Fig. 5, the reference numeral Ill may denote, generally, a control system wherein a circuit breaker I0 of the type such as is shown and described in connection with Fig. 1 of the drawings, may be utilized with control means II and regulating means Ill which may be responsive to load current, reactive kva., or voltage, as shown, for connecting a bank of capacitors I02 to a power system or load circuit designated, Benerally, by the conductors I which may connect a load and a source, through contact members Illa, I01) and I0c.

The circuit breaker closing solenoid I24 may be energized in the usual manner by a circuit breaker switch I06 and a cutoff relay I31, and the circuit breaker may be tripped by a shunt trip device 91 and a trip relay I38 under the control of the regulating means I3I. Overload trip means 30 and manual trip means 39 may also be provided. A control switch 53 provides a normally closed operating circuit for eflecting closure of the circuit breaker from one control conductor I40 through conductor I4I, contact members "a, normally closed contact members Illa of the cutoff relay I31, operating winding I40 of the circuit breaker switch I36, contact members I9Ib and contact arm I of the voltage control or regulating relay I! to the other control conductor I4b. Operation of the control switch 53 maybe effected by means of an operating member 51, which is supported in operating relation to the control switch 53 by means of the support member in the manner described in connection with Fig. 1. Operation of the support member 50 in the clockwise direction to render the operating member 51 ineffective to operate the control switch, may be effected by means of the manual trip device 39 or the shunt trip device 31 which actuate the arm 64 in the manner described in connection with Fig. 1 of the drawings.

With the capacitors I32 connected to the load circuit conductors I39, as shown, the voltage or regulating relay III may operate to disconnect the capacitors whenever the voltage of the circuit conductors I39 reaches a predetermined upper value. When this value is reached, the contact arm I45 engages theupper contact member Illa. providing an energizing circuit for the trip relay III, which completes a circuit for the shunt trip device 91 through contact members Illa and con- 7; tact members Me of the circuit breaker. The circuit breaker I is tripped, but the control switch 53 remains in the closed position, since the operating member 51 is actuated to the nonoperating position by the arm 64 through operation of the shunt trip device.

' Whenever the voltage of the load circuit conductors I33 reaches a predetermined relatively low value, the contact arm I45 of the voltage relay I3I engages the lower contact member-I3 lb and provides an operating circuit for the circuit breaker switch I36, efiecting energization of the operating winding I34 of the circuit breaker and closure of the circuit breaker. The cutoff relay I31 is energized through a circuit extending through contact members I0d of the circuit breaker, and operates to deenergize the operating winding I43 of the circuit breaker switch in the usual manner.

' In the event that the circuit breaker I0 is tripped through operation of the over-current device 36, the operating member 51 of the control means II remains in the operating position. Accordingly, when the circuit breaker opens, the actuating member 55 of the control switch 53 is moved downwardly by the operating member 51, opening contact members 53a. The operating circuit for the circuit breaker switch I36 is thereby interrupted, so that the voltage or regulating relay I3I is rendered ineffective to reclose the circuit breaker and it remains locked out until attended to by the operator.

Referring to Fig. 6, the reference numeral I50 may denote, generally, a control system for a circuit breaker 18 provided with control means 60 embodying the principal features of the inven tion, and which may be disposed to provide for the connection of a bank of capacitors I32 to aload circuit designated generally by the conductors I33 which may connect the load circuit to a suitable source, through contact members 16a, 16b and m and their disconnection therefrom under the control of a regulating device responsive to load current, reactive kva, or voltage conditions, such as, for example, the voltage regulating device I3I.

Operation of the circuit breaker I8 may be eil'ected by providing an operating circuit for the motor 96 of the circuit breaker by means of a master relay I52 through contact members I 52c thereof and contact members d of the circuit breaker. The master relay operatin circuit extends through the normally closed contact members I06a of a control switch I06, contact members I54a of a control relay, operating winding I55, and contact members I3Ia.

With the. circuit breaker. 18 closed and the system operating, as shown. with the capacitors I32 connected to the load circuit conductors I33, the contact arm I45 of the voltage relay I3I' may operate to engage the lower contact member I 3I b whenever the voltage of the load circuit conductors reaches a predetermined maximum value. This provides an energizing circuit for the control relay I54 through contact members I52b of the master relay. The control relay operates and opens contact members I54a, interrupting the energizing circuit of the master control relay I52. The master relay opens, providing an energizing circuit for the shunt trip device 03 through the normally open contact members I52d and contact members 18c of the circuit breaker. The shunt trip device operates, releasing the latch mechanism designated gen 1 erally by the numeral I51 and opening the cir- 8 cuit breaker. The control switch-l06 remains in the closed position since the operating member I08 is retained in the operated position by the latch member II 6.

If the voltage of the load circuit conductors I33 reaches a predetermined minimum value, the contact arm I45 of the voltage relay I3I engages the upper contact member I3Ia and provides an energizing circuit for the operating winding I 55 of the master relay I52 through contact members I54a of the control relay and contact members I060 of the control switch. The master relay operates, providing an energizing circuit for the operating motor through contact members I520 and eiiecting closure of the circuit breaker. A holding circuit for the master relay is provided through its contact members I52a.

Should a fault occur so as to produce an overcurrent condition, the over-current device 96 operates, and the armature I02 actuates the trip member III5a and, at the same time, operates the latch member H6 to release the operating member I08 of the control switch I06. The contact members I06a 'of the control switch open, interrupting the operating circuit for the operating winding I55 of the master relay, so that reclosure of the circuit breaker may not be efiected without resetting the control switch I06.

From the above description and the accompanying drawings, it will be apparent that we have provided, in a simple and eiiective manner, for securing a selective operation of a control switch in response to predetermined operations of the circuit breaker operating mechanism. By thus operating the control switch, selective control of the circuit breaker may be obtained so as to prevent reclosing of the circuit breaker, when it has opened in response to an over-current condition, without preventing reclosing oi. the circuit breaker when it has opened for other reasons.

Since certain changes may be made in the above description, and diflferent embodiments of the invention may be made without departing from the spirit or scope thereof, it is intended that all the matter contained in the above description, or shown in the accompanying drawing, shall be considered as illustrative and not in a limiting sense.

We claim as our invention:

1. The combination with a circuit breaker having an operating mechanism and control means including a plurality of means operable to open the circuit breaker and means to reclose it, of control means operable to effect energization of one of the circuit breaker opening means and the closing means in response to predetermined voltage conditions of a circuit, and switch means operable in response to operation of another one of the opening means connected to prevent reclosing of the circuit breaker.

2. A control system for a circuit breaker having control means operable to close the breaker and trip means operable to trip the circuit breaker comprising, means responsive to different predetermined voltage conditions of a power circuit for efiecting operation of the closing and trip means to close and trip the circuit breaker, a control switch providing an operating circuit for the closing means, means operable in response to an over-current condition in the power circuit to eifect operation of the trip means, and means actuated by the said over-current responsive means for eilecting operation of the control switch to interrupt the operating circuit for the closing means.

3. The combination with a circuit breaker having an operating mechanism actuated under the control of closing means and trip means, of a control switch having normally closed contact members providing an operating circuit for the additional control means responsive to operation of the control means, operable to render the operating means ineffective to operate the control switch.

4. The combination with a circuit breaker having an operating mechanism operated by closing means and trip means, of a control switch normally providing an operating circuit for the closing means, operating means including a plurality of pivotally connected levers actuated by the circuit breaker mechanism to actuate the control switch and open the operating circuit when the circuit breaker opens, control means operable in response to a predetermined electrical condition in anelectric circuit to operate the trip means, and additional control means responsive to a fault condition operable to operate the trip means and actuate one of the said levers to alter the operation of the operating means and render it inoperative to actuate the control switch.

5. A control system for a circuit breaker having an operating mechanism actuated by closing means and trip means operable by a plurality of control means comprising, a control switch provided with actuating means normally providing an operating circuit for the closing means,

operating means for actuating the switch means in response to opening of the operating mechanism including a lever carrying means for engaging the switch actuating means, plvotally mounted support means supporting the lever in switch operating relation, and means operable in response to operation of one of the control means to trip the circuit breaker and actuate the movable support means to move the lever out of switch engaging relation.

6. A circuit breaker comprising, relatively movable contact members having an operating mechanism with a breaker bar movable with the moving contact member and a trip bar operatively connected to the mechanism for tripping the mechanism to open the circuit breaker, means responsive to over-current conditions for actuating the trip bar to open the circuit breaker. electrically operated closing means for actuating the breaker bar to close the circuit breaker, a control switch providing a normally closed operating circuit for the closing means, operating means for actuating the control switch in response to movement of the breaker bar, additional means cooperative with the trip bar to open the circuit breaker, and means actuated by said additional means operable to render the operating means inoperable to actuate the control switch.

releasing it to open the circuit breaker, a control switch providing a normally closed circuit for the closing means, means for actuating the control switch comprising an operating member actuated by the opening or the circuit breaker and a pivotally mounted support member positioning the operating member in operating relation with the control switch, over-current means operable to actuate the trip means to open the circuit breaker, and control mean operable to actuate the trip means and the support member so as to move the operating member out of operating relation with the control switch.

8. The combination with a circuit breaker having an operating mechanism with closing means for operating it to close the circuit breaker and trip means for releasing it to open the circuit breaker, of control means actuated by the breaker providing a normally closed operating circuit for the closing means, latch means retaining the control switch in the closed position, means responsive to overcurrent for operating the trip means to open the circuit breaker, and means responsive to operation of the over-current means for operating the latch means to release the control switch.

9. The combination with a circuit breaker having an operating mechanism with closing means and trip means, of switch means providing a closed operating circuit for the closing means, a movable operating member operable to actuate the switch means, latch means engaging the operating means to retain it in the operated position, means responsive to over-current for operating the trip means to open the circuit breaker and operate the latch means to release the actuating member, means operatively connecting the operating member to the circuit breaker operating mechanism for reengaging the operating member in response to closure of the circuit breaker, and means movably supporting the latch means actuable to reengage the operating member and return the switch means to the operated position to provide an operating circuit for the closing means.

10. A control system for a power circuit comprising, load means, circuit breaker means having closing means operable to close the circuit breaker and connect the load means to the power circuit and a plurality of trip means operable to open the circuit breaker, control means responsive to predetermined conditions of the power circuit for providing operating circuits for either the closing means or one of the trip means, a control switch normally providing an operating circuit for the closing means, and means mechanically actuated by another of the trip means for effecting operation of the control switch to interrupt the operating circuit of the closing means.

11. A control system for controlling the connection oi electrical apparatus to an electrical circuit comprising, circuit breaker means having an operating mechanism with closing means for operating it to close the circuit breaker and connect the electrical apparatus to the electrical circuit and trip means for releasing the mechanism to open the circuit breaker, a control switch having normally closed contact members providin an operating circuit for the closing means, shunt trip means for operating the trip means to open the circuit breaker, means responsive to predetermined conditions of the electrical circuit for effecting operation of the closing means and the shun-t trip means to connect and disconnect the electrical apparatus and the electrical circuit, means responsive to an overcurrent through the electrical device to and disconnect it from the power system. means responsive to voltage conditions of the power system for effecting operation of the circuit breaker means, a control switch having normally closed contact members providing an operating circuit for the closing means, an operating member for effecting movement of the control switch, means responsive to overcurrent for operating the trip means, and means operable in response to operation of the over- 'means and trip means operable to connect the 10 current means for efl'ectlng operation of the control switch to interrupt the closing circuit.

WILLIAM H. CUT1'INO.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number 7 Name Date 1,605,015 Travers et al. Nov. 2, 1926 1,718,448 Yamazaki June 25, 1929 1,718,516 Anderson June 25, 1929 1,962,943 Seeley June 12, 1934- 2,059,836 Anderson Nov. 3, 1936 2,060,494 Gamel Nov. 10, 1936 2,298,026 Bany Oct. 12, 1934 2,336,836 Barry Dec. 14, 1943

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